JPH0510970B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention focuses on core particles (hereinafter referred to as base particles).
Either fine metal particles (hereinafter referred to as child particles) are attached to the surface of the mother particle in advance or they are not attached to the surface of the mother particle, and the metal child particles are fixed to the surface of the mother particle, and then all or part of the metal child particles are subjected to impact. This invention relates to a method of spreading and fixing metal onto the surface of base particles by spreading with a type impact means. Conventionally, it has generally been used to prevent caking of solid particles, prevent discoloration and deterioration, improve dispersibility, improve flowability, improve catalytic effect, control digestion and absorption, improve magnetic properties, improve color tone, improve light resistance, and be useful. Various surface modifications are used to reduce the amount of (expensive) substances used, including electrochemical methods, physical adsorption methods, chemical adsorption methods, vacuum evaporation methods, electrostatic deposition methods, coating methods for dissolved substances, and special spray drying methods. It has been done in such a way. Among these, in particular, when the surface of solid particles is modified with metal solid particles, that is, the surface of powder is modified with metal powder, it is necessary to modify the surface of solid particles with metal powder for a long time ( Stir for several hours to several tens of hours,
Modification has been carried out by applying the electrostatic and mechanochemical phenomena that occur with stirring, but the adhesion of the child particles to the mother particle is reduced by simply adhering the metal child particles around the mother particle. Therefore, when the modified powder is mixed, kneaded, dispersed, made into a paste, etc. in the next process, the child particles may easily fall off or the ingredients may be unbalanced, resulting in poor operating conditions. Not only did this significantly limit the quality of the product, but it was also the biggest cause of variations in the quality of processed products. Furthermore, in surface modification of powder-metal powder systems using the above-mentioned various mixers, ball mills, etc., since the fixing force of child particles to the mother particle surface is generally weak, it is difficult to obtain the desired surface modification. This process requires several hours to several tens of hours, resulting in large equipment and problems such as poor processing efficiency. The present invention has been made in view of the above-mentioned circumstances, and solves the problems of the prior art.As shown in FIG. If necessary, thermal means can be used as an auxiliary means to forcibly spread and fix all or part of the metal particles, creating a uniform and stable powder in an extremely short period of time (several seconds to several minutes). This provides a method for surface-modifying particles and thereby obtaining a functional composite material (hybrid powder).The gist of the method is to place a rotating disk surrounded by impact pins in an impact chamber. At the same time, a collision ring is arranged along the outermost orbital surface of the impact pin and with a certain space therebetween, and the airflow generated by the rotation of the impact pin is directed between the impact material and the impact ring. A powder composed of solid particles and other metal solid particles smaller than the solid particles is guided and circulated from a part of the rotary disk to a circulation circuit that opens in the front cover near the center of the rotary disk, and together with the air flow, a powder consisting of solid particles and other metal solid particles smaller than the solid particles is The entire amount of the anti-particle group is repeatedly passed through the impact chamber via the circulation circuit, and the other metal solid particles are applied to the surface of the solid particles by mechanical impact between the impact pin and the collision ring. The present invention provides a method for spreading and fixing metal onto the surface of solid particles, which comprises fixing the solid particles, and then spreading and solidifying the solid metal particles by the continuous mechanical impact. Typical base particle powders that can be surface-treated by the method of the present invention generally have an average particle diameter of 0.1 μm to
Calcium carbonate, carrion, which is about 100μm
Inorganic materials such as alumina, silica sand, glass beads, and titanium dioxide; metals such as copper, lead, zinc, tin, and iron; and metal compounds; and organic synthetic polymer materials such as epoxy powder, nylon powder, polyethylene powder, and polystyrene powder; They are organic natural materials such as starch, cellulose, and silk powder, and representative metal particle powders (sometimes acicular or thread-like) include gold, which generally has a particle size of about 0.01 μm to 10 μm. ,
These include fine powders of silver, copper, zinc, tin, iron, lead, stainless steel, nickel, aluminum, titanium, cadmium, and their oxide powders and compound powders. However, these powders are not limited to the above materials, but are also used in various chemical industries,
Applicable to various combinations of materials used in industries such as electricity, magnetic materials, cosmetics, paints, printing inks, toners, colorants, textiles, pharmaceuticals, foods, rubber, plastics, and ceramics. be able to. Generally, large-sized parent particles and small-sized child particles are used as the parent particles, but depending on the combination of material particle sizes, the child particles of the parent particles may be reversed. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 2 and 3 show an example in which an impact type crusher is used as the impact type striking means. In all the figures, 1 is the casing of the powder impact device (typical impact crusher) used to carry out the method of the present invention, 2 is the rear cover, 3 is the front cover, and 4 is the inside of the casing 1. A rotary disk 4 rotates at high speed, and reference numeral 5 denotes a plurality of impact pins radially arranged around the outer periphery of the rotary disk 4 at predetermined intervals, and these are generally hammer-shaped or plate-shaped. 6 is a rotary shaft that rotatably supports the rotary disk 4 within the casing 1;
Reference numeral 8 denotes a collision ring which is disposed around the outermost orbital surface of the impact pin 5 and with a certain space therebetween, and this can be of various concave and convex shapes or of a circumferential flat plate type. Reference numeral 9 denotes an on-off valve for discharging modified powder, which is provided by cutting out a part of the collision ring, and in some cases, this may be provided by cutting out a part of the front cover or rear cover facing the grinding chamber. . 10 is a valve shaft of the on-off valve 9; 11 is an actuator that operates the on-off valve 9 via the valve shaft 10; 13 has one end opening into a part of the inner wall of the collision ring 8; and the other end opening into the rotary disk 4. A circulation circuit that opens in the front cover near the center to form a closed circuit, 14 a raw material hopper, 15 a raw material supply chute connecting the raw material hopper 14 and the circulation circuit 13, 16 a raw material measuring feeder, 17
is the raw material storage tank. Reference numeral 18 indicates a shock chamber provided between the outer periphery of the rotary disk 4 and the collision ring 8, and reference numeral 19 indicates a circulation port to the circulation circuit 13. 20 is a modified powder discharge chute, 21 is a cyclone, 22 is a rotary valve, 23 is a back filter, 24 is a rotary valve, 25 is an exhaust fan, 31 is a time control device for controlling the operation of this device, and 32 is a preset Various types of mixers, electric mortars, and other known preprocessors used when it is necessary to attach child particles to the surface of particles are shown. When carrying out the method of the present invention using the above-mentioned apparatus, it is operated in the following manner. First, the on-off valve 9 for discharging the reformed powder is kept closed, and the rotating shaft 6 is moved by a driving means (not shown) while introducing air or an inert gas into the device as necessary. The rotary disk 4 is rotated at a circumferential speed of 5 m/sec to 160 m/sec depending on the nature of the substance to be modified. At this time, a rapid airflow of air/inert gas is generated as the impact pin 5 on the outer periphery of the rotary disk 4 rotates, and the circulation circuit 13 opens into the impact chamber 18 due to the fan effect based on the centrifugal force of this airflow. A circulating flow of air flows from the circulation port 19 through the circulation circuit 13 and back to the center of the rotary disk 4, that is, a completely self-circulating flow is formed. Furthermore, since the amount of circulating air generated per unit time is significantly larger than the total volume of the shock chamber and circulation system, an enormous number of air circulation cycles are formed in a short period of time. Next, a powder to be treated is prepared by attaching child particles to the surface of a certain amount of mother particles using electrostatic phenomenon, or a physical property that acts as a binder such as a small amount of water or various organic solvents is interposed to form a mother particle. The powder to be treated with child particles attached to the surface of the particles is transferred to the weighing feeder 1.
6, the raw material is fed into the hopper 14 in a short time. When it is not necessary to use the preprocessor 32, the mother particles, child particles, and some binder are weighed separately and charged into the raw material hopper 14. The powder to be processed passes from the raw material hopper 14 through the chute 15 and enters the shock chamber 18 . The powder particles sent into the impact chamber 18 are instantaneously impacted by a large number of impact pins 5 of the rotary disk 4 rotating at high speed, and further collide with the surrounding impact ring 8 to form a matrix. All metal particles on the particle surface are selectively subjected to strong compression. At the same time, the powder to be treated is circulated through the circulation circuit 13 along with the flow of the circulating gas, returns to the impact chamber 18, and is again subjected to the impact action. This type of impact operation is repeated many times in a row in a short period of time, and the metal particles are strongly spread on the surface of the base particle, and furthermore, by receiving (thermal) energy from the impact and impact action, The metal child particles are firmly fixed to the surface of the mother particle within a short time. This series of impact operations, that is, the work of spreading and fixing the metal particles on the surface of the base particle, is continued until the entire surface of the base particle is locally or completely brought into the desired spread and fixation state. Since a large amount of gas (air and inert gas) circulates in the system compared to the total volume of the circulation system, the powder to be processed (base particles and metal particles) that circulates with the gas is We will receive a huge number of shocks. Although it depends on the amount of treatment per batch, the time required for this spreading and fixing is generally completed within an extremely short time of several seconds to several minutes, even including the time for supplying the powder to be treated. Figure 1 shows a model diagram. In the figure, the mother particle,
The metal particle is not limited to a spherical shape. Figures 1 and 2 show a state in which metal particles b and b' are attached to base particles a and a' by static electricity or a very small amount of binder. As a result of the action, the surface of the metal particles is extended as shown in FIGS. 3 to 5, and adhesion or overlapping of the metal particles occurs partially or entirely.
Fixed. In addition, various combinations of metal particles,
Depending on the order of supply, as shown in FIGS. 6 to 8, different metal particles b and c can be spread and fixed in a single layer or in multiple layers on a base particle a. After the above spreading and fixing work is completed, the on-off valve 9 for discharging the treated powder is moved to the position shown by the chain line and opened, and the treated powder is discharged. This spread and immobilized powder is exposed to the centrifugal force acting on itself (as long as the centrifugal force is acting on the treated powder, the discharge valve 9 may be located at a different location).
Then, it is discharged from the shock chamber 18 and the circulation circuit 13 in a short period of time (several seconds) by the suction force of the exhaust fan 25, and is discharged from the cyclone 21 and circulation circuit 13 through the chute 20. 21 and a bag filter 23, the powder is collected and discharged to the outside of the system via rotary valves 22 and 24. After discharging the spread and immobilized powder, the on-off valve 9
was immediately closed, and from the weigh feeder 16 again,
A certain amount of powder to be treated from the next time onward is supplied to the impact chamber, and processed powder is produced one after another through the same process. Note that these series of batch fixing processing operations are controlled and continued by a time limit control device 31 whose time limit is set in advance in relation to the operating time of related equipment. If the spreading and immobilization of the metal particles onto the surface of the base particle requires partial local immobilization, the powder impacting device shown in FIG. 2 can also be used as a one-pass color continuous processing system. In that case, the powder to be treated may be continuously supplied from the raw material hopper 15 with the circulation port 19 in FIG. 2 closed and the on-off valve 9 open. In addition, when it is necessary to use supplementary thermal treatment during the spreading and fixing treatment operation (for example, when it is necessary to increase the degree of adhesion between the base particles and the metal particles), the collision ring 8 or Circulation circuit 13
By using a jacket structure, it is possible to set temperature conditions convenient for spreading and fixing the powder to be treated through various heating mediums and heating mediums. In addition, in the powder impacting device used in the present invention, auxiliary blades are attached to the rotary disk 4, or a centrifugal plate fan or the like is placed in the middle of the circulation circuit 13 to further apply force to the circulation flow. You can also give. That is, if the circulating air volume is increased, the number of times of circulation within a unit time increases, and therefore the number of collisions of powder particles also increases, so that the spreading and fixing processing time can be shortened. Furthermore, the powder impact device used in the present invention is
Not only the one equipped with the above-mentioned circulation circuit, but also the second
It is also possible to use the apparatuses shown in FIGS. 3 and 3 in which the circulation circuit is removed. Next, during the powder work performed in the powder impacting device used in the present invention, various impurities such as nitrogen gas are used to prevent oxidative deterioration during spreading and fixation of the powder to be processed, and to prevent ignition and explosion. The case of using active gas will be explained. FIG. 4 shows an example in which this inert gas is used in the powder impact device used in the present invention. In the description of this embodiment, the same members as in the previous embodiment are designated by the same reference numerals, and the explanation thereof will be omitted.
In FIG. 4, 26 is a raw material supply valve provided at the bottom of the raw material hopper 14, 27 is an inert gas supply valve that opens into the raw material supply chute 15, 28 is an inert gas supply source, and 29 is an inert gas supply valve. This shows the supply route. Note that this embodiment shows an embodiment in which the circulation circuit 13 is housed within the casing 1. When starting the operation, first, the raw material supply valve 26 is closed, the on-off valve 9 is opened, and then the inert gas supply valve 27 is opened to fill the shock chamber 18 and circulation circuit 13 with inert gas. The substitution of inert gas into the shock chamber and circulation circuit prior to the start of this immobilization work is usually completed within a few minutes. Next, after closing the on-off valve 9 and the supply valve 27 at the same time, the raw material supply valve 26 is immediately opened, and the pre-measured powder to be processed is passed through the chute 15 into the shock chamber 1.
Supply to 8. After supplying, the supply valve 26 is immediately returned to the closed state, and upon receiving this signal, the weighing feeder 16 measures and supplies the next powder to be processed to the raw material hopper 14. Thereafter, the powder to be treated is impacted with an inert gas in the same manner as in the above embodiment, and the powder to be treated is spread and fixed while circulating in the circulation circuit 13 while maintaining sufficient contact with the inert gas. processed. Next, when the on-off valve 9 and the supply valve 27 are opened, the powder that has been spread and fixed is discharged from the shock chamber 18 and circulation circuit 13 to the chute 20, and at the same time, the shock chamber 18 and circulation circuit 13 are replaced by gas. The discharged spread and fixed powder is treated in the same manner as in the previous example. Thereafter, by closing the on-off valve 9 and the supply valve 27 and opening the raw material supply valve 26, the next spreading and fixing treatment operation will proceed. Note that this series of batch fixing operations including supply and stop of the inert gas are controlled and continued by the time control device 31 as in the previous embodiment. If the fixation of the metal particles onto the surface of the base particle can be carried out by spreading and fixing the particles locally, the powder impacting device shown in FIG. 4 can be used as a one-pass color continuous processing system. In that case, the circulation circuit 13 shown in FIG. It is sufficient to supply it at a ratio of . At this time, if a method is adopted in which the inert gas at the outlet of the exhaust fan (25 in FIG. 2) is returned to the raw material supply chute 15, the amount of inert gas used can be reduced, which is economical. As mentioned above, the feature of the method for spreading and fixing metal on the surface of solid (powder) particles according to the present invention is that it utilizes the strong impact force on the fine powder particles of the impact type crushing mechanism as the impact type impact means. In order to apply an impact force to the metal particles attached to the entire surface of the base particle having a certain shape while the fine powder particles are completely dispersed in the gas phase in the device system, The reason is that the magnitude of the impact force itself and the number of impacts can be adjusted as desired. Therefore, it is possible to completely prevent various kinds of fine powders on the micron order, which tend to aggregate, from adhering to each other, and at the same time, it is possible to apply just the right amount of impact force to each of the fine powders. It is possible to produce modified powders of various quality in a short time, with good color development such as the color and shine unique to metals. Furthermore, as shown in FIG. 1, according to the method of the present invention, the spreading and fixing of metal particles to the mother particles of various materials is not limited to simply spreading and fixing a single particle layer using single-component metal particles; It is possible to perform microencapsulation in which the particles are coated in a film, spreading and fixing of metal particles of two or more components, and further spreading and fixing in multiple layers of metal particles of one or more components. In addition, the shape of the metal particle is spherical, irregular,
The shape, such as fibrous shape, is not limited. Furthermore, according to the method of the present invention, when the ratio (ratio) of the spread and immobilized metal child particles to each base particle does not need to be so strict (that is, when the overall component ratio only needs to be constant), , without using a preprocessor such as a mixer or an electric mortar, separately weighed base particle powder and metal particle powder are directly supplied to the impact chamber to spread and fix the metal particle onto the surface of the base particle. can be done. As described above, according to the method according to the present invention,
A functional composite powder material (composite or hybrid powder) that has uniform and stable properties by performing surface modification treatment to spread and fix metal particles on the base particles, which are made of a combination of various powder materials. can be produced efficiently in an extremely short time. Example 1 The powder impact device shown in FIG. 2 was used, in which the outer diameter of eight plate-type impact pins disposed around a rotary disk was 235 mm, and the diameter of the circulation circuit was 54.9 mm. Ordered mixers are prepared by adhering silver powder particles for conductive paints with an average particle size dp50 = 0.5 to 3 μm on the surface of spherical nylon 12 with an average particle size dp50 = 15 μm as base particles using a mixer, respectively, under the treatment conditions shown in the table below. As a result of the spreading and fixing treatment, the silver powder for conductive paints (metallic particles) was spread and fixed on the surface of Nylon 12 (base particles, core particles), resulting in uniform and stable surface modification of Nylon 12 with silver powder for conductive paints. A powder was obtained.

Calculated from [Table] and the internal volume of the circulation circuit.

[Brief explanation of the drawing]

1 to 8 are conceptual explanatory diagrams showing various aspects of the powder before treatment and the powder after spreading and fixation according to the method according to the present invention, and FIG. 2 shows the powder impacting device used in the present invention. A conceptual explanatory diagram systematically showing one example along with its front and rear devices, Fig. 3 is a side cross-sectional explanatory diagram of Fig. 2, and Fig. 4 is an explanatory diagram of another device when using an inert gas. show. a... Mother particles, b, c... Child particles, 1... Impact type crusher.

Claims (1)

[Scope of Claims] 1. A rotary disk surrounding an impact pin is arranged in an impact chamber, and a collision ring is arranged along the outermost orbital surface of the impact pin and with a certain space therebetween. , the airflow generated by the rotation of the impact pin is guided and circulated through the impact chamber and a circulation circuit that opens from a part of the impact ring to the front cover near the center of the rotary disk; In addition, the entire amount of the powder particle group consisting of solid particles and other metal solid particles smaller than the solid particles is repeatedly passed through the impact chamber via the circulation circuit, and the impact pin and the collision ring are A solid characterized in that the other metal solid particles are fixed to the surface of the solid particles by mechanical impact between the solid particles, and the metal solid particles are further spread and immobilized by the continuous mechanical impact. A method for spreading and fixing metal onto particle surfaces. 2. The surface of the solid particle according to claim 1, characterized in that the solid particle and another metal solid particle are mixed in advance and the other metal solid particle is attached to the surface of the solid particle. Method of spreading and fixing metal to. 3. Spreading of metal on the surface of the solid particle according to claim 1, wherein all or part of the metal solid particles adjacent to each other on the surface of the solid particle overlap and are immobilized. Fixing method. 4. The method for spreading and fixing metal onto the surface of a solid particle according to claim 1, characterized in that heating is used as an auxiliary means to strengthen the adhesion between the solid particle and the metal solid particle. 5. The method for spreading and fixing metal onto the surface of solid particles according to claim 1, characterized in that the spreading and fixing step is carried out under an inert gas atmosphere.